#include<bits/stdc++.h>
using namespace std;
int main(){
	float x,y,z;
	cin>>x>>y>>z;
	printf("%.1f",x*8.5+y*5.6+z*6.2);
}
/**************************************************************
	Problem: 1610
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/